Nature of Genetic Load in Relation to Diversity in Pennisetum

The differences between some populations of Pennisetum for the nature and magnitude of genetic load (as chlorophyll recessives) were examined. Diverse mechanisms were found to operate in the differentiation of these populations, the most potent of them being the ecological factors and the genetic drift. The persistence of these chlorophyll deficiencies was examined from the view point of natural selection, heterozygote superiority, the changes in the genetic background, linkage equilibrium and epistasis. The limited studies on the changes in chiasma frequency under inbreeding pointed to the existence of yet another mechanism, the cytological homeostasis, that helps to maintain a balanced genetic load through the regulation of recombination. The balanced genetic load, the diversity and potential variability of the African populations appear to have enabled them to adapt to a variety of geographical conditions as compared to the limited potential of the Indian collections. Therefore, the use of African lines in breeding programmes to ensure a greater stability of performance and adaptability over a wide range of environmental conditions in this country is recommended.